Recording element having a crosslinked polymeric layer

ABSTRACT

A recording element having at least one layer comprising a crosslinked polymer having polymeric backbone moieties and crosslinking moieties, the polymeric backbone moieties containing tertiary nitrogen atoms, the crosslinking moieties connecting polymeric backbone moieties at the teritary nitrogen atoms by conversion of the tertiary nitrogen atoms to quaternary amine, the crosslinking moiety having the structure ##STR1## where R&#39; is independently alkyl or aryl and m is an integer of from 1 to 10.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to recording elements and more particularly tophotographic image recording elements having at least one layercontaining a crosslinked polymer providing improved physical properties.

In addition, the invention relates to a method of making such improvedrecording elements.

2. Description of Related Art

Because of the sensitive nature of recording elements, particularlyimage recording elements and most particularly photographic imagerecording elements, it is an ongoing quest to find improved materialshaving physical properties that are compatible with the nature of theimaging element while at the same time providing improved physicalproperties especially with respect to abrasion resistance. While theinvention is applicable to all types of recording elements, such asmagnetic elements, optical disks, etc., it is especially applicable tophotographic image recording elements. Therefore, throughout theremainder of this specification the invention will be described withrespect to photographic elements. However, it is to be understood thatthe invention is applicable to all types of recording elements.

During the manufacture of photographic elements, for example, the filmin various stages of completeness of manufacture is engaged by numeroussurfaces including planar surfaces, rollers, and the like, and the filmis rolled into huge rolls one layer upon the other for storage duringthe course manufacture. Once a photographic film has completed thecourse of manufacture, it is still subjected to various forces in theexposure stage of its life including physical handling by thephotographer, engagement of various surfaces in the various types ofcameras in which it is employed and finally during the development stagewhen it can be subjected to numerous contacts in various types ofdevelopment apparatus. During all of these operations, injury can besustained by the film which will be demonstrated in the final product;thereby rendering the product, the image contained thereon, eitherinferior or useless.

Therefore, there is a need in the imaging art and particularly in thephotographic arts to manufacture elements that are extremely resistantto any form of deterioration, especially with regard to contact withother materials including transport materials for moving the film fromone location to another because of the damage that is likely to occur inthese areas. Also, there is a need for photographic elements having atleast one layer containing a crosslinked polymeric material that ishighly abrasion-resistant, such as overcoat layers, subbing layers,transparent magnetic recording layers, the binder employing crosslinkedpolymeric material in accordance with this invention. In addition,thereis a need for polymers for use in recording layers wherein a materialhaving a greatly enhanced Tg and modulus is required.

SUMMARY OF THE INVENTION

The invention contemplates a recording element having at least one layercomprising a crosslinked polymer having polymeric backbone moieties andcrosslinking moieties, the polymeric backbone moieties containingtertiary nitrogen atoms, the crosslinking moieties connecting polymericbackbone moieties at the tertiary nitrogen atoms, the crosslinkingmoiety having the structure: ##STR2## where R¹ is independently alkyl oraryl and m is an integer of from 1 to 10.

The invention also contemplates a method of making the crosslinkedpolymer by reacting a polymeric tertiary amine containing linear orbranched polymer with a trialkoxysilylbenzyl halide ortriaryloxysilybenzyl halide and then subjecting the product thereof tomoisture.

DETAILED DESCRIPTION OF THE INVENTION

The invention contemplates a recording element, having at least onelayer containing a crosslinked polymer having polymeric backbonemoieties and crosslinking moieties that join the polymeric backbonemoieties at tertiary nitrogen atoms contained in the polymeric backbonemoiety. In this regard, the polymeric backbone moiety preferably shouldcontain from about 1 to about 10 mole percent of tertiary nitrogenatoms.

The invention contemplates any and all types of polymeric backbonemoieties containing tertiary nitrogen atoms. The tertiary nitrogen atomsmay be present within the polymeric backbone or on pendant groupsattached to the polymeric backbone. The invention is applicable tolinear polymers having polymeric backbone moieties so long as theycontain tertiary nitrogen atoms.

Suitable polymers containing tertiary nitrogen atoms includepolycondensation polymers, such as, polyesters, polyethers,polythioethers, polyurethanes, polyamides, and the like; polyadditionpolymers include addition products of ethylenically unsaturated monomerswhich contain tertiary nitrogen atoms and the like.

Suitable polyesters include those prepared employing glycols, a portionof which contain tertiary nitrogen atoms such as,N-methyldiethanolamine, N-butyldiethanolamine, N-oleyldiethanolamine,N-cyclohexyldiisopropylamine, N,N-dihydroxyethyl-p-toluidine, and thelike. Suitable polyesteramides containing tertiary nitrogen atomsinclude those prepared by replacing a portion of the conventional glycolor the teritary amine containing glycol used in the preparation of thepolyesters set forth above with organic diamines or amino alcohols, suchas ethylene diamine, 1,4-butane diamine, 1,6-hexane diamine, tolylenediamine, 4,4'-diaminodiphenylmethane, 1,4-cyclohexylenediamine,aminoethyl alcohol, aminobutyl alcohol, aminooctyl alcohol, caprolactan,and the like.

Suitable polythioethers include condensation products of thiodiglycolwith itself and with/other glycols such as ethylene glycol,1,2-propylene glycol, and the like, and glycols containing tertiarynitrogen atoms, for example, N,N-dihydroxyp-ethyl-aniline and the like.

Suitable polyethers containing tertiary nitrogen atoms include thereaction product of an alkylene oxide, such as, ethylene oxide orpropylene oxide with any of the tertiary amine containing diols setforth above for use in preparation of polyesters.

Polyaddition polymers containing tertiary nitrogen atoms includecopolymers of ethylenically unsaturated monomers with tertiary aminecontaining unsaturated monomers such as dimethyl aminoethylmethacrylate, dimethyl aminoethyl acrylate, diethyl aminoethylmethacrylate, diethyl aminoethyl acrylate, N-methyl, N-ethyl amino ethylacrylate, and the like. Suitable ethylenically unsaturated monomers tocopolymerize with the tertiary amine containing monomers includestyrene, vinyl toluene, methyl acrylate, methyl methacrylate, butylacrylate, acryamide, and the like. Suitable addition polymers are setforth in U.S. Pat. No. 4,439,322 which is incorporated herein byreference.

While the invention is applicable for crosslinking any linear polymercontaining tertiary nitrogen atoms, it is particularly applicable forthe crosslinking of polyurethane polymers including polyurethane-ureasbecause of the presence of tertiary nitrogen atoms in many of suchpolymers and because of the ease with which tertiary nitrogen atoms canbe incorporated into such polymers.

Polyurethane polymers are the reaction product of an organicdiisocyanate with a polymeric diol and a chain extending agent. Thetertiary nitrogen atoms may be present in the polymeric diol in themanner indicated previously, however, it is generally preferred toutilize a tertiary amine containing diol or diamine chain extendingagent to incorporate the tertiary nitrogen atoms. The tertiary nitrogenatoms may be present in a portion of the chain extending agent and inthis embodiment, other chain extending agents are used in addition tothose containing tertiary nitrogen atoms. Any suitable polymeric diolmay be used in the preparation of the polyurethane such as, for example,hydroxyl polyesters, hydroxyl polyesteramides, polyethylene etherglycols, dihydric polythioethers, polyacetals and the like.

Any suitable substantially linear hydroxyl polyester may be used suchas, for example, the reaction product of a dicarboxylic acid and adihydric alcohol and also polyesters prepared from lactones such ascaprolactone and the like. Any suitable dicarboxylic acid may be used inthe preparation of polyesters such as, for example, adipic acid,succinic acid, suberic acid, sebacic acid, oxalic acid, methyladipicacid, glutaric acid, pimelic acid, azelaic acid, phthalic acid,isophthalic acid, thiodiglycollic acid, thiodipropionic acid, maleicacid, fumaric acid, citraconic acid, itaconic acid and the like. Anysuitable dihydric alcohol may be used in the reaction with thedicarboxylic acid to form a polyester, such as, for example, ethyleneglycol, propylene glycol, hexanediol, bis-(hydroxymethyl cyclohexane),1,4-butanediol, diethylene glycol, polyethylene glycol, 2,2-dimethylpropylene glycol, xylylene glycol, and the like. Any suitable polyesteramide may be used by replacing some of the glycol used in thepreparation of hydroxyl polyesters with an organic diamine, an aminealcohol or a lactam such as, ethylene diamine, 1,4-butane diamine,1,6-hexane diamine, 1,4-pentane diamine, 2,4 and 2,6-tolylene diamine,4,4'-diamino diphenylmethane, xylylene diamine, 1,4-cyclohexane diamine,phenylene diamine, naphthalene diamine, aminoethyl alcohol, aminopropylalcohol, aminobutyl alcohol, aminooctyl alcohol,hydroxyethyl-aminoethylether, caprolactam, Δ-valerolactam and the like.

Any suitable polyalkylene ether glycol may be used such as, for example,the condensation product of an alkylene oxide with a compound containingtwo active hydrogen atoms such as, for example, water, ethylene, glycol,propylene glycol, butylene glycol, amylene glycol, hydroquinone,pyrocatechol, pyrogallol, N-ethyl aminoethanol, N-methyl diethanolamineand the like. Any suitable alkylene oxide condensate may also be usedsuch as, for example, the condensates of ethylene oxide, propyleneoxide, butylene oxide, amylene oxide, styrene oxide and mixturesthereof. The polyalkylene ethers prepared from tetrahydrofuran may beused, such as, polytetramethylene ether glycols. The polyhydricpolyalkylene ethers may be prepared by any known process such as, forexample, the process described by Wurtz in 1859 and in the "Encyclopediaof Chemical Technology" Volume 7, pages 257 to 262, published byInterscience Publishers in 1951, or in U.S. Pat. No. 1,922,459.

Any suitable dihydric polythioether may be used such as, for example,the reaction product of one of the aforementioned aklylene oxides usedin the preparation of the polyhydric polyalkylene ether with apolyhydric thioether such as, for example, thiodiglycol, 3,3'-dihydroxypropyl sulfide, 4,4'-dihydroxy butyl sulfide, 1,4-(3-hydroxyethyl)phenylene dithioether and the like.

Any suitable chain extending agent may be employed in the preparation ofthe polyurethane polymer such as, for example, ethylene glycol,propylene glycol, 1,4-butanediol, 1,3-butane diol, 1,5-pentanediol,1,6-hexanediol, xylyene glycol, diethylene glycol, thiodiglycol,p-phenylene-di-3-hydroxyethylether, neopentyl glycol, and the like. Whenthe tertiary nitrogen atoms are present in the chain extending agent,any suitable compound may be employed such as, for example,N-methyldiethanolamine, N-propyl diethanolamine, N-butyldiethanolamine,N-oleyldiethanolamine, N-cyclohexyldiethanolamine,N-methyldiisopropanolamine, N-cyclohexyldiisopropanolamine,N-methylbis(2-aminoethyl)amine, N-butylbis-(3-aminopropyl)amine,N-cyclohexylbis (3-amino-propyl)amine, and the like.

Any suitable organic diisocyanate may be used in the preparation ofpolyurethane polymers containing tertiary nitrogen atoms in accordancewith this invention, such as, for example, aliphatic, aromatic,alicyclic and heterocyclic diisocyanates including such as, for example,ethylene diisocyanate, ethylidene diisocyanate, propylene diisocyanate,butylene diisocyanate, cyclopentylene-1,3-diisocyanate,cychlohexylene-1,4-diisocyanate, cyclohexylene-1,2-diisocyanate,2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate,4-4'-diphenyl-methane diisocyanate,2,2-diphenylpropane-4,4'-diisocyanate,3,3'-dimethyldiphenylmethane-4,4'-diisocyanate, p-phenylenediisocyanate, m-phenylene diisocyanate, xylylene diisocyanate,1,4-naphthylene diisocyanate, 1,5-naphthylene diisocyanate,diphenyl-4,4'-diisocyanate, azobenzene-4,4'-diisocyanate,diphenylsulfone-4,4'-diisocyanate, dichlorohexamethylene diisocyanate,tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylenediisocyanate, 1-chlorobenzene-2,4-diisocyanate, furfurylidenediisocyanate, isophorone diisocyanate, 2,4-diisocyanatodibenzofuran andthe like.

In the preparation of the polyurethane polymer, all of the ingredientsmay be mixed together simultaneously and allowed to react. A suitablemethod is to cast the material onto a slab where it is permitted tosolidify. Also, the polymeric diol and the isocyanate may be firstreacted together to form a isocyanate terminated prepolymer and thisprepolymer subsequently reacted with the chain extending agent to obtaina polyurethane polymer having tertiary nitrogen atoms.

Suitable polycondensation polymers containing tertiary nitrogen atomsare set forth in U.S. Pat. Nos. 4,286,022; 4,608,397; 4,271,217;4,310,565; 4,328,282; 4,420,530; 4,182,828; 4,152,307; 4,128,538;4,097,642; 4,054,592; 4,046,725; and 4,001,305, all of which areincorporated herein by reference.

In a preferred embodiment poly(dimethylsiloxane) blocked polyurethaneelastomers are formed from the reaction in stoichiometric amounts of:

(a) an aliphatic diisocyanate and

(b) a polyol selected from the group consisting of polyester basedpolyols, polyether polyols, polycarbonate polyols, acrylic polyols andmixtures thereof and

(c) a poly(dimethylsiloxane) having the structure ##STR3## Wherein the Jand J' groups are independently selected from alkyl aminopropyl,hydroxyl, alkoxy or carboxylate. Preferably, J and J' are the same. R6,R7, R8, R9, and R10 are independently aryl, alkyl, or fluoroalkyl thealkyl portion of which contains from 1 to 5 carbon atoms, and the valuesof X and Y are each from 0 to 400, such that X+Y is from 50 to about400, and

(d) a short chain aliphatic diol chain extender and

(e) a short chain aliphatic diol which contains tertiary nitrogen, suchas, any of the tertiary amine containing glycols set forth above in thepreparation of polyesters. N-methyl diethanolamine is preferred.

The polysiloxane content varies optimally over a range of 1 to 10 weightpercent. The overall molecular weight varies, but optimally it is from40,000 to 100,000. The glass transition temperatures of the polymersvaries.

The method in accordance with this invention contemplates the reactionof the backbone moiety with a trialkoxysilylbenzyl halide or atriaryloxysilybenzyl halide having the general formula ##STR4##

where R' represents alkyl, aryl, or mixtures thereof, X representshalogen atoms such as, fluorine, chlorine, bromine or iodine and m is aninteger of from 1 to 10, with 1 being preferred. The silane substituentmaybe ortho, meta, or para with para being preferred.

Representative crosslinking agents include, but are not limited toortho, meta, and para position isomers of the following:

chloromethylphenyltrimethoxysilane

chloromethylphenyltri-n-propoxysilane

bromomethylphenyltriphenoxysilane

1-iodo-3-propylphenyltri-n-butyoxysilane

1-bromo-6-hexylphenyltriphenoxysilane

1-iodo-10-decaphenyltriethoxysilane

fluoromethylphenyltrimethoxysilane

chloromethylphenyldiethoxyphenoxysilane and the like.

Throughout the remainder of this application for simplicity inexpression, the para isomer is referred to. However, this should not beconsidered limiting on the scope of the invention.

The trialkoxysilylbenzyl halide or a triaryloxysilybenzyl halide isreacted with the polymeric moiety containing tertiary nitrogen groups ina suitable solvent to form the quaternized polymer having the generalformula ##STR5## Unlike the situation in many polymeric quaternizationreactions, the polymer salt does not precipitate, but rather stays insolution and is not isolated. The polymer solution is then coated on asuitable support or if a free-standing film is desired, the polymersolution is coated on a low energy surface such as Teflon and allowed todry under ambient conditions. Ambient moisture will then cause the filmto crosslink in accordance with the following equation: ##STR6##

The free-standing film prepared as described above may be employed as asupport for magnetic recording, photographic elements, and the like. Thesolution containing the reaction product of the polymeric moietycontaining tertiary nitrogen atoms and the trialkoxysilylbenzyl halideor a triaryloxysilybenzyl halide may be employed as a binder for any ofthe layers in a recording element such as, for example, as the binder ina magnetic recording element, as the binder for any of the layers of aphotographic element such as, for example, U-coat layers, intermediatelayers, backing layers, antistat layers, antihalation layers, overcoatlayers, and the like. Other ingredients such as, for example, antistaticagents, including vanadium pentoxide and those disclosed in U.S. Pat.Nos. 4,394,441; 4,418,141; 4,495,276; and in Research Disclosure 308119,December 1989, Section XIII; matte beads, lubricating agents, as setforth in Sections XVI and XII respectively of Research Disclosure308119, and the like may be incorporated into any of the layers inaccordance with commonly and conventionally known technology. Thecrosslinked polymeric compositions in accordance with this invention areparticularly suitable as overcoat layers for photographic elementsbecause of their toughness and abrasion resistant properties.

The following examples further define the invention but do not limit it.The following polymers were prepared and the polymers exemplary of theinvention are summarized.

EXPERIMENTAL

The synthesis of the polydimethylsiloxane polyurethane block copolymersused the following materials:

Tetrahydrofuran (THF), dried over Type 4A Molecular Sieves for 24 hoursbefore use.

RMDI--Desmodur W (4,4'-dicyclohexylmethane diisocyanate), sold by MilesCo.

Polycaprolactone (TONE), sold by Union Carbide.

N-Methyldiethanolamine (MDEA), sold by Aldrich Chemical Co.

Amino propyl terminated polydimethylsiloxane PS 510, sold by HulsAmerica.

POLYMER 1 Preparation of Polyurethane/Poly(dimethylsiloxane) CopolymersContaining Tertiary Nitrogen Atoms

In a 3-neck, round bottom flask equipped with a stirrer, condenser and anitrogen inlet, 44.28 g (0.3375 eq) of RMDI and 5 drops of dibutyltindiluarate were dissolved in 100 g of THF. The flask was heated to 40° C.with stirring and 35.78 g (0.135 eq) of Polycaprolactone (TONE 0200),0.23 g (0.00018 eq) PS510 and 100 g of THF were added. With continuedmixing, the reaction was heated to 65° C.-70° C. for approximately 3hours. The reaction was cooled to 40° C. and 12.06 g (0.2025 eq) MDEAand 50 g THF were added followed by increased heating to 65° C.-70° C.while stirring for 24 hours at which time all the free NCO groups wereconsumed. The product was isolated in heptane and dried in a vacuum ovenat 50° C. for 3 days.

The above reaction is a general procedure for the synthesis of apolydimethylsiloxane (PDMS)/polyurethane block copolymer. The followinglist shows the compositional variation of the soft segment and how thesechanges can produce PDMS copolymers with different properties. Each ofthe following reactions uses the same procedure as Example 1.

POLYMER 2

{PDMS-TONE(RMDI-MDEA} with 25 wt % PS510 and

Tone 0210

Tone 0210=56.02 g (0.135 eq)

PS 510=0.28 g (0.00022 eq)

Hard Segment/Soft Segment=50/50 wt %

POLYMER 3

{PDMS-TONE(RMDI=MDEA)RMDI} with 1 wt % PS 510 and

Tone 0210

Tone 0210=56.02 g (0.135 eq)

PS 510=1.12 g (0.00089 eq)

Hard Segment/Soft Segment=50/50 wt %

POLYMER 4

{PDMS-TONE(RMDI-MDEA)RMDI} with 1 wt % PS 510 and

Tone 0200

Tone 0200=35.78 g (0.135 eq)

PS 510=0.92 g (0.00074 eq)

Hard Segment/Soft Segment=60/40 wt %

POLYMER 5

{PDMS-TONE(RMDI-MDEA)RMDI} with 3.00 wt % PS 510 and

Tone 0200

Tone 0200=35.78 g (0.135 eq)

PS 510=2.76 g (0.0022 eq)

Hard Segment/Soft Segment=59/41 wt %

POLYMER 6

{PDMS-TONE(RMDI-MIDEA)RMDI} with 3.00 wt % PS 510 and

Tone 0210

Tone 0210=56.02 g (0.135 eq)

PS 510=3.37 g (0.0027 eq)

Hard Segment/Soft Segment=49/51 wt %

POLYMER 7

{PDMS-TONE (RMDI=MDEA) RMDI} with 3.00 wt % PS 510 and

Tone 0200

Tone 0200=39.75 g (0.15 eq)

PS 510=2.65 g (0.0021 eq)

Hard Segment/Soft Segment=53/47 wt %

POLYMER 8

{PDMS-TONE (RMDI-MDEA) RMDI} with 3.00 wt % PS 510 and

Tone 0200

Tone 0200=35.29 g (0.1329 eq)

PS 510=2.84 g (0.0023 eq)

Hard Segment/Soft Segment=59/41 wt %

POLYMER 9

{PDMS-TONE(RMDI-MDEA)RMDI} with 3 wt % PS 510 and

Tone 0200

Tone 0200=25.89 g (0.0977 eq)

PS 510=2.90 g (0.0023 eq)

Hard Segment/Soft Segment=71/29 wt %

POLYMER 10

{PDMS-TONE(RMDI-MDEA)RMDI} with 3 wt % PS 510 and

Tone 0200

Tone 0200=12.75 g (0.0593 eq)

PS 510=23.1 g (0.0018 eq)

Hard Segment/Soft Segment=80/20 wt %

Polymers 1-3 and 7-10 were crosslinked into free-standing polyurethanefilms as illustrated in the following example:

18.0 g of the polyurethane containing 0.00107 mol tertiary nitrogen/gpolymer was dissolved in 184 g THF. To 40 ml of this solution was added0.90 g (stoichiometric amount) of p-chloromethylphenyltrimethoxysilane.The solution was stirred at room temperature for 50 minutes and thencast in a Teflon dish. The solvent was allowed to evaporate underambient conditions.

Dynamic mechanical analysis (DMA) was used to measure the mechanicalproperties of the linear and crosslinked polyurethanes. The measurementswere made on a Rheometrics Solid Analyzer (RSA-II) at temperaturesgenerally between minus 150° C. and plus 200° C. The driving frequencyof the instrument was 10 Hz. The sample dimensions were 7.5 mm wide, 23mm long and approximately 0.1 mm in thickness. The storage modulus (E')(Pa) of the linear polymers and crosslinked in accordance with theinvention are set forth in Table 1.

    ______________________________________                                                       Storage Modulus                                                Polymer        at 130° C.                                              ______________________________________                                         1 Comparison  <10.sup.6                                                       1 Invention   2 × 10.sup.8                                              2 Comparison  <10.sup.6                                                       2 Invention   9 × 10.sup.7                                              3 Comparison  <10.sup.6                                                       3 Invention                                                                   7 Comparison  <10.sup.6                                                       7 Invention   6 × 10.sup.7                                              8 Comparison  <10.sup.6                                                       8 Invention   9 × 10.sup.7                                              9 Comparison  <10.sup.6                                                       9 Invention   2 × 10.sup.8                                             10 Comparison  <10.sup.6                                                      10 Invention   3 × 10.sup.8                                             ______________________________________                                    

The data set forth in Table 1 was extracted from DMA curves of many ofthe linear and crosslinked elastomers described in the examples. Theresults show that the physical properties of the polyurethanes aregreatly improved by crosslinking in accordance with the invention. Ingeneral, the storage modulus (E') is nearly constant to nearly the Tg ofthe linear polymers but in each example the Tg is less than 60° C. Thereis then a marked decrease in E' dropping 3-4 orders of magnitude in lessthan 20 degrees. At higher temperatures the polymer enters into itsviscous flow regime. In addition, the maximum in the loss modulus peak(E") is rather sharp for the linear polyurethanes.

After crosslinking, dramatic changes in both the storage and lossmodulus are observed. The storage modulus is still constant to near theTg of the crosslinked elastomer in each example. The most profoundchanges are observed above the Tg. Above the Tg the storage modulusdrops only 1-2 decades. By crosslinking the polyurethane, the servicetemperature is extended by over 100° C.

What is claimed is:
 1. A photographic element comprising a support, atleast one light-sensitive silver halide containing layer and a layercomprising a crosslinked polymer having polymeric backbone moieties andcrosslinking moieties, the polymeric backbone moieties containingtertiary nitrogen atoms, the crosslinking moieties connecting polymericbackbone moieties at the tertiary nitrogen atoms by conversion of thetertiary nitrogen atoms to quaternary amine, the crosslinking moietyhaving the structure ##STR7## where R¹ is independently alkyl or aryland m is an integer of from 1 to
 10. 2. The photographic element ofclaim 1 wherein m is
 1. 3. The photographic element of claim 1 whereinthe tertiary nitrogen atoms are present in pendant groups.
 4. Thephotographic element of claim 1 wherein the polymeric backbone moietiesare polycondensation polymers.
 5. The photographic element of claim 1wherein the polymeric backbone moieties are polyaddition polymers. 6.The photographic element of claim 1 wherein the polycondensationpolymers are polyurethane polymers.
 7. The photographic element of claim1 wherein the polyurethane polymers comprise a polymeric diol, a chainextending agent, and an organic diisocyanate.
 8. The photographicelement of claim 1 wherein the chain extending agent contains tertiarynitrogen atoms.